Not Applicable
Not Applicable
The present invention relates generally to equipment for and methods of testing and characterizing micro-optics, and more particularly to interferometers for and interferometric methods of testing and characterizing such components.
The with advent of optical communications, there has been a sudden demand for suitable equipment for testing and characterizing the very small, micro-optical components, or xe2x80x9cmicro-opticsxe2x80x9d, that are used as a part of optical network infrastructure. Such components include, for example, very small lenses for focusing a laser beam, modulated with information, into and out of each fiber of a fiber optic cable. The micro-optics, typically ranging from approximately 10 xcexcm to 3 mm in diameter, are mass produced, and therefore must be tested and characterized to ensure that they meet predetermined specifications prior to installation. Such testing must be thorough, accomplished in minimal time and be accurate.
The present invention is an improved system specifically adapted to automatically test and characterize a plurality of micro-optics.
In accordance with one aspect of the invention, a system comprises:
(a) a micro-optical component support constructed and arranged so as to support an array of micro-optical components under test;
(b) an interferometer constructed and arranged for generating a test beam for use in testing micro-optical components under test; and
(c) a controller constructed and arranged so as to automatically move the support and test beam relative to one another while moving the reference surface so as to automatically and sequentially test the micro-optical components.
In one preferred embodiment the interferometer comprises:
(i) a source of radiation constructed and arranged so as to define a beam of radiation,
(ii) system components, including a system component defining a reference surface, constructed and arranged so as to define at least two paths for the beam so that the beam can be separated into at least a test beam and a reference beam, the test beam being directed toward the support, and the reference beam being directed to the reference surface; and
(iii) a reference support constructed and arranged so as to move the reference surface so as to vary the path length of the reference beam.
The system component defining the reference surface can include a curved surface that defines the reference surface and determined by the specifications of each of the micro-optical components, wherein the curved surface is preferably a spherical surface. The system comprises structure to allow the selection of either a source of long coherent radiation or a source of short coherent radiation depending upon the test performed by the system. The source of coherent radiation is preferably selected when testing the transmission characteristics of the each of the micro-optical components, the source of short coherent radiation is selected when testing the reflection characteristics of each of the micro-optical components.
The micro-optical component support is preferably adapted to move in two mutually orthogonal directions each substantially normal to the path of test beam, while the reference support is movable in a direction substantially parallel to the path of the test beam.
In another embodiment the interferometer includes a second reference support for supporting a return reflecting surface for receiving the test beam transmitted through each micro-optical component, and reflect the test beam back through the micro-optical component under test. The second reference support is also preferably movable in a two mutually orthogonal directions each substantially normal to the path of the test beam so as to adjust the lateral position of the return reflecting surface relative to the test beam so that a focal point of the reference surface is properly positioned relative to a focal point of the micro-optical component under test.
In accordance with yet embodiment a micro-optical component holding structure, attached to the interferometer, is provided for holding each micro-optical component relative to the test beam.
Another embodiment the micro-optical component support structure includes pick-up structure for picking up each micro-optical component.
And in another embodiment, the micro-optical support structure includes structure constructed and arranged so as to pick up each micro-optical component, move the component relative to the test beam so as to properly position the micro-optical component, and hold the micro-optical component relative to the test beam during testing of the micro-optical component.
In a preferred embodiment the micro-optical structure includes a vacuum chuck assembly constructed and arranged so as to pick up and hold each micro-optical component relative to the test beam, wherein the vacuum chuck assembly includes a geocentric positioning device for positioning the micro-optical component relative to the test beam.
In accordance with another aspect of the invention, a system comprises:
(a) a micro-optical component support constructed and arranged so as to support an array of micro-optical components under test;
(b) an interferometer constructed and arranged for generating a test beam for use in testing micro-optical components under test;
(c) micro-optical component holding structure, attached to the interferometer, for holding each micro-optical component relative to the test beam; and
(d) a controller constructed and arranged so as to automatically pick up and holding each micro-optical component with the holding structure.
In one embodiment the micro-optical component holding structure includes pickup structure for picking up each micro-optical component.
In another embodiment, the micro-optical holding structure includes structure constructed and arranged so as to pick up each micro-optical components move the component relative to the test beam so as to properly position the micro-optical component, and hold the micro-optical component relative to the test beam during testing of the micro-optical component. The micro-optical holding structure preferably includes a vacuum chuck assembly constructed and arranged so as to pick up and hold each micro-optical component relative to the test beam. The vacuum chuck assembly preferably includes a geocentric positioning device for positioning the micro-optical component relative to the test beam.
In accordance with another aspect of the invention, a system for testing micro-optical components having at least one optically curved surface, comprises:
(a) a support for supporting at least a micro-optical component under test;
(b) a source of a beam of radiation directed along a beam path;
(c) a beam divider constructed and arranged so as divide the beam of radiation so as to generate a test beam along a test beam axis and a reference beam along a reference beam axis;
(d) a first objective lenses system positioned so as to direct the reference beam on a corresponding micro-optical reference component positioned on the reference beam axis positioned a first predetermined distance from the beam divider and reflect an image of the reference component on the beam divider;
(e) a second objective lenses system positioned so as to direct the test beam on a micro-optical reference component under test positioned a second predetermined distance from the beam divider and reflect an image of the component under test on the beam divider; and
(f) imaging optics for imaging the interference pattern created by the reflection of the image of reference component and the image of the component under test.
In one embodiment, the source of a beam of radiation if a short coherent light source. In another embodiment the first and second predetermined distances are substantially the same, and the system further includes structure for adjusting either the first or second predetermined distance so as to create phase-shifting between the test and reference beams.
In yet another embodiment the reference component is a sphere, and the sphere is opaque.